PHOENIX — Tom Coughlin is still trying to get the hang of this smartphone thing.

Determined to prove you can indeed show an old dog new tricks, the NFL’s oldest coach revealed Wednesday at the NFL owners meetings that he has an iPhone and is willing to use it.

It hasn’t been easy, though, as the Giants’ 68-year-old field boss found out recently when he reluctantly tried out Siri — the phone’s voice assistant — for directions to his grandson’s roller-hockey game in suburban New Jersey.

“I don’t [usually] trust the lady in GPS because they don’t send you the right way,” Coughlin said during the NFC coaches breakfast. “So I hit the button, and she gives me directions and find out where I am. And I say, ‘Thank you very much, I know exactly where I am.’ And she comes back and says, ‘You don’t have to thank me.’ I swear to God!’’

Coughlin’s astonishment didn’t end there, though.

“And then I couldn’t get her to shut up!” he said, his voice rising. “She was like, ‘Take a right here,’ and I’m like, ‘I know where I am — I’m a block from my house!’’’

Modern technology was one of Coughlin’s favorite topics during his hour-long press sitdown as he good-naturedly tried to bust some stereotypes about himself and his ability to relate to a locker room filled with twenty-somethings.

She was like, ‘Take a right here,’ and I’m like, ‘I know where I am — I’m a block from my house!’

- Tom Coughlin

The impetus, Coughlin revealed, was a study the Giants recently did on the psychology of the so-called Millennial generation (people born between the early 1980s and early 2000s) so he and the team’s front office could get a better understanding of their players.

What did that study show?

“[They are good at] multi-tasking and incredibly versatile when it comes to the technological things that are available today,” Coughlin said. “They would rather text than call. You can’t get them to answer the phone.”

Coughlin apparently took the results of that study and ran with them, getting the iPhone and learning how to text. Two weeks ago, he said, he even learned how to access the Internet on it.

It was Giants VP of player evaluation Marc Ross who showed Coughlin how to use Siri.

“Yeah, I know how to text,” Coughlin said. “I can text. I’m not like you [reporters], though. I’m a hunt-and-peck guy.”

Coughlin also said he was motivated to become more tech-oriented by offensive coordinator Ben McAdoo, whom Coughlin described as “a guy who can wheel and deal with all this new technology.”

Coughlin admits his tech conversion continues to be slow going and wouldn’t be possible without the help of two of his young grandchildren, whom he relies on as his personal IT department.

His grandkids’ mastery of all things tech seemed to ​awe​​ Coughlin as much as his ability to converse with Siri.

“If I don’t know how to do something, my 11-year-old grandson and 11-year-old granddaughter help me out with it,” Coughlin said. “When I was raised, it was: ‘Don’t touch that [technology]! You’ll break it! Don’t you dare touch that!’ But they have no fear of that now. They just go and do it, because they’ve been reinforced by people saying, ‘You can’t hurt it.’’’

Coughlin admitted he has no such luck.

“I can hurt it,” he said of the devices. “I defy all odds when it comes to that.”